The rain poured during the third round at the Open Championship, and it created carnage at Royal Troon. Pros exist in precise little windows, but with the rain comes added variables. It makes playing golf a lot more complicated, in four ways specifically …

1. Knuckling

The main issue the rain creates is that it produces knuckleballs. The wet golf ball slides up the wet clubface, and the reduced friction between the two makes it harder for the grooves to grab the ball. It reduces the amount of backspin players hit the ball with, which can send the ball wobbling unpredictably as it moves through the air.

“When it’s wet, you never have enough control off the face,” says Justin Rose, who comes into Sunday one shot back at three under.

2. Skidding

The wet clubface-wet ball interaction means the ball comes out with less backspin. And whatever backspin it does have can’t grab the surface of the green as well, because the grass is also wet. It means the ball skids forward upon landing which, again, is difficult to judge.

3. Twisting

Perhaps the most obvious effect the rain has on golfers comes in the rough. When the longer grass is sopping wet, it’s simply harder to swing your club through it. It means that when the clubhead interacts with the grass, it starts twisting around—especially if your hands and grips are wet.

Luke Walker/R&A

“The most important thing is trying to get the ball in the fairway, because from the rough you can’t reach the green,” Rose said.

4. Deadening

As if the above three factors weren’t enough, there’s also a general ‘deadening’ effect from the rain. The ball is interrupted by lots of little raindrops as it flies through the air. It’s like driving with the handbrake on, and at times it can be impossible to judge.

“When the rough is dry…you can get the ball to jump. When it’s wet, it basically never comes out hot. It’s either going to come out dead or come out nowhere,” says Justin Thomas, who comes into Sunday four shots back. “The moisture, it’s hard to explain, but it changes everything.”

This article was originally published on golfdigest.com